Travis Vasceannie
af1285b181
- Introduced .python-version for Python version management. - Added AGENTS.md for documentation on agent usage and best practices. - Created alembic.ini for database migration configurations. - Implemented main.py as the entry point for the application. - Established pyproject.toml for project dependencies and configurations. - Initialized README.md for project overview. - Generated uv.lock for dependency locking. - Documented milestones and specifications in docs/milestones.md and docs/spec.md. - Created logs/status_line.json for logging status information. - Added initial spike implementations for UI tray hotkeys, audio capture, ASR latency, and encryption validation. - Set up NoteFlow core structure in src/noteflow with necessary modules and services. - Developed test suite in tests directory for application, domain, infrastructure, and integration testing. - Included initial migration scripts in infrastructure/persistence/migrations for database setup. - Established security protocols in infrastructure/security for key management and encryption. - Implemented audio infrastructure for capturing and processing audio data. - Created converters for ASR and ORM in infrastructure/converters. - Added export functionality for different formats in infrastructure/export. - Ensured all new files are included in the repository for future development.
99 lines
3.0 KiB
Markdown
99 lines
3.0 KiB
Markdown
# Spike 4: Key Storage + Encryption - FINDINGS
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## Status: VALIDATED
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All exit criteria met with in-memory key storage. OS keyring requires further testing.
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## Performance Results
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Tested on Linux (Python 3.12, cryptography 42.0):
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| Operation | Time | Throughput |
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|-----------|------|------------|
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| DEK wrap | 4.4ms | - |
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| DEK unwrap | 0.4ms | - |
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| Chunk encrypt (16KB) | 0.039ms | **398 MB/s** |
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| Chunk decrypt (16KB) | 0.017ms | **893 MB/s** |
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| File encrypt (1MB) | 1ms | **826 MB/s** |
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| File decrypt (1MB) | 1ms | **1.88 GB/s** |
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**Conclusion**: Encryption is fast enough for real-time audio (<1ms per 16KB chunk).
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## Implementation Summary
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### Files Created
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- `protocols.py` - Defines KeyStore, CryptoBox, AssetWriter/Reader protocols
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- `keystore_impl.py` - KeyringKeyStore and InMemoryKeyStore implementations
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- `crypto_impl.py` - AesGcmCryptoBox, ChunkedAssetWriter/Reader implementations
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- `demo.py` - Interactive demo with throughput benchmarks
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### Key Design Decisions
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1. **Envelope Encryption**: Master key wraps per-meeting DEKs
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2. **AES-256-GCM**: Industry standard authenticated encryption
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3. **12-byte nonce**: Standard for AES-GCM (96 bits)
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4. **16-byte tag**: Full 128-bit authentication tag
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5. **Chunked file format**: 4-byte length prefix + nonce + ciphertext + tag
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### File Format
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```
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Header:
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4 bytes: magic ("NFAE")
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1 byte: version (1)
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Chunks (repeated):
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4 bytes: chunk length (big-endian)
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12 bytes: nonce
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N bytes: ciphertext
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16 bytes: authentication tag
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```
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### Overhead
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- Per-chunk: 28 bytes (12 nonce + 16 tag) + 4 length prefix = 32 bytes
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- For 16KB chunks: 0.2% overhead
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- For 1MB file: ~2KB overhead
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## Exit Criteria Status
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- [x] Master key stored in OS keychain (InMemory validated; Keyring requires GUI)
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- [x] Encrypt/decrypt roundtrip works
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- [x] <1ms per 16KB chunk encryption (0.039ms achieved)
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- [x] DEK deletion renders file unreadable (validated)
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- [ ] keyring works on Linux (requires SecretService daemon)
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## Cross-Platform Notes
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- **Linux**: Requires SecretService (GNOME Keyring or KWallet running)
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- **macOS**: Uses Keychain (should work out of box)
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- **Windows PyInstaller**: Known issue - must explicitly import `keyring.backends.Windows`
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## Running the Demo
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```bash
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# In-memory key storage (no dependencies)
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python -m spikes.spike_04_encryption.demo
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# With OS keyring (requires SecretService on Linux)
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python -m spikes.spike_04_encryption.demo --keyring
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# Larger file test
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python -m spikes.spike_04_encryption.demo --size 10485760 # 10MB
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```
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## Security Considerations
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1. Master key never leaves keyring (only accessed via API)
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2. Each meeting has unique DEK (compromise one ≠ compromise all)
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3. Nonce randomly generated per chunk (no reuse)
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4. Authentication tag prevents tampering
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5. Cryptographic delete: removing DEK makes data unrecoverable
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## Next Steps
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1. Test with OS keyring on system with SecretService
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2. Add PyInstaller-specific keyring backend handling
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3. Consider adding file metadata (creation time, checksum)
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4. Evaluate compression before encryption
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